1. Field of the Invention
The present invention relates to a transparent conductive film using an indium tin oxide (ITO) layer.
2. Description of the Related Art
A transparent electrode plate, in which three layers of indium tin oxide are laminated on a glass substrate, is well-known (For instance, Japanese Unexamined Patent Application Publication No. JP 08-43840 A). In a transparent electrode plate in JP 08-43840 A, the content of tin oxide (SnO2) contained in a first layer and a third layer of indium tin oxide is greater than the content of tin oxide contained in a second layer of indium tin oxide. This makes it possible to minimize a surface resistance value of the transparent electrode plate.
Since a sputtering layer of indium tin oxide is amorphous, the sputtering layer has a high surface resistance value as deposition. To minimize the surface resistance value of the sputtering layer, it is necessary to crystallize, the indium tin oxide by heat treatment (crystallization treatment). In JP 08-43840 A, the temperature and time of crystallization treatment are typically 200° C., 60 minutes.
However, when a film substrate is used instead of a glass substrate, it is impossible to perform a crystallization treatment at a high temperature (about 200° C.) like the case of a glass plate due to low heat resistance of the film substrate. Accordingly, when a film substrate is used, there are problems that it is impossible to perform a crystallization treatment on the indium tin oxide or it takes too much time to perform a crystallization treatment in the conventional constitution of three layer-indium tin oxide.